In a blog post on Thursday, Microsoft revealed that it has fixed the problem, meaning that developers can start submitting new apps to the Windows Phone Marketplace again.

"We fixed the digital certificate problem and last evening resumed publishing new apps. It will take a day or two for the repair to fully deploy and newly-published apps to begin appearing in Marketplace again," Microsoft's Todd Brix said in the blog.

"If your app was in the process of being published, you don't need to take any action. We have applied the fix and the app will continue through the certification and publishing workflow as normal."

However, the Redmond based firm has yet to sort out the issue that has left some users unable to update an existing app, and is advising Windows Phone users to wait until it fixes the issue before trying to do so again.

"Some customers who try to download a new app may see an error message. If they're attempting to update an existing app, they might repeatedly be prompted to retry the update. We don't recommend that people uninstall these apps because they might not be able to download and use them again until we deploy our fix," Brix added.

"We've already identified the problem and are working to resolve it and resume certifying and publishing apps as quickly as possible. I apologize for any inconvenience caused." µ